Statement of Purpose: Cardiac dysfunction, specifically myocardial infarction (MI) ranks among the major causes of morbidity and mortality in current times. Intramyocardial therapeutics injection is an efficient method of enhancing cardiac performance after experiencing ischemic MI. Myeloid-derived growth factor (Mydgf) is a newly found protein secreted by bone marrow-derived monocytes and macrophages. It is responsible for cardiac myocyte survival, angiogenesis, and shows promise in promoting cardiac recovery after MI. Additionally, Mydgf shows angiogenic activity by motivating the migration and tubular formation of human umbilical vessel endothelial cells (HUVECs). Moreover, Mydgf has been shown to protect cardiomyocytes from apoptosis. However, in order to maintain the protein level, several days of continuous perfusion is needed, which severely limits the clinical translation of this protein. Here, we introduce an injectable polyester hydrogel which is capable of loading Mydgf with an extended release capability in vivo and demonstrate an innovative new potential treatment of MI. Methods: Citrate acid was reacted with hexaethylene.